Liquid Crystal Displays (LCDs) or Organic Light-Emitting Diode (OLED) displays are increasingly replacing traditional Cathode Ray Tube (CRT) displays in some applications due to their low radiation, small volume, low power consumption and other advantages. Thus, LCDs or OLEDs have been widely applied to notebook computers, Personal Digital Assistants (PDAs), flat panel TV sets, mobile phones and other information products. In the traditional liquid crystal display, a chip on a panel is driven by an external driver chip to display an image, but in order to reduce the number of elements and the production cost, the driver has been developed gradually in recent years by being fabricated directly on the display panel, for example, in such a scheme a gate driver is integrated on a Gate driver On Array (GOA).
As compared with the traditional Chip On Flex/Film (COF) and Chip On Glass (COG) processes, the GOA technology may save the cost and enable both sides of the panel to be symmetric, and this technology is primarily characterized in that GOA units are triggered consecutively to function as shift registers, so as to dispense with an bounding area of gated Integrated Circuits (Ws) and a space for Fan-out wiring, to thereby realize a design of a narrow edge frame; and moreover a bonding process in the direction of gates may be saved to thereby improve the yield and the qualified ratio.
The gate driver in the GOA technology has been optimized in the prior art to thereby ensure a stable output. For example, in order to prevent a timing from becoming out of order due to a delayed clock signal or another reason, in the GOA technology the respective shift register units output sequentially, and the respective clock signals have duty ratios below 50% and overlap sequentially by less than half the width of a pulse, so that an output signal of a current shift register unit overlaps with an output signal of a preceding shift register unit by less than half the width of a pulse. However there may be still a problem with the gate driver in the GOA circuit in some cases, for example, in the GOA circuit, some shift register units depend upon an output signal of a shift register unit preceding thereto, and takes the output signal of the shift register unit preceding thereto as an input signal of the current shift register unit, and if the shift register unit preceding thereto fails or is invalid so that the output signal of the preceding shift register unit becomes abnormal, then the current and succeeding shift register units may not output any signal normally, that is, the entire GOA circuit may operate improperly and even become inoperative.